Comparison between Transareola Singlesite Endoscopic Thyroidectomy and Minimally Invasive Video-assisted Thyroidectomy

Abstract

OBJECTIVES:

To compare surgical outcomes between transareola single-site endoscopic thyroidectomy (TASSET) and minimally invasive video-assisted thyroidectomy (MIVAT).

Methods:

Patients with thyroid nodules were randomized to TASSET (n = 24) or MIVAT (n = 24). Surgical outcomes and patient-rated cosmetic results, based on numerical (0 [worst], 10 [best]) and verbal (1 [poor], 4 [excellent]) response scales, were compared.

Results:

There were no significant differences between groups for age, sex, indication for operation, estimated blood loss, postoperative pain and length of postoperative stay. TASSET was associated with a significantly longer mean ± SD operative time than MIVAT (156.84 ± 41.42 vs. 66.38 ± 17.58 min), and significantly improved cosmetic results according to the numerical (9.63 ± 0.60 vs 7.90 ± 1.38) and verbal response (3.8 ± 0.5 vs 3.1 ± 0.7) scales. Postoperative complaints were comparable between the two approaches, although MIVAT involved a shorter operation time.

Conclusions:

Patients treated with TASSET had superior cosmetic results compared with those treated with MIVAT.

Introduction

Over the last decade, there has been a global trend towards minimally invasive approaches to thyroidectomy.^1,2 Traditional thyroidectomy offers a high level of safety and has reached a high therapeutic standard, but is associated with extensive scarring in the anterior neck. Thyroid nodules occur mostly in women, who tend to be concerned about the aesthetic appearance of scars after thyroidectomy. Minimally invasive, totally gasless, video-assisted thyroidectomy (MIVAT) via an approximate 2-cm incision in the neck was introduced in 1997, ³ and has become the most frequently used minimally invasive thyroidectomy technique worldwide. Ever since endoscopic neck surgery was introduced in 1996, ⁴ various types of endoscopic thyroidectomies have been devised using axillary, anterior chest, breast, dorsal or hybrid approaches to improve cosmetic outcome.^{5 – 8} These surgical approaches enable a smaller wound size or allow for the positioning of the wound in areas of cosmetic benefit. The transaxillary approach has a better cosmetic result than other routes due to having an ‘invisible' scar in the neutral position. This procedure requires a wide dissection area to reach the target site from the axillary region, however.

Laparoendoscopic single site surgery (LESS) is a recent development in minimally invasive surgery, and is used as a viable surgical approach in gallbladder, appendix, bariatric and other surgical fields because of the reduction in scars and postoperative pain.^{9 – 12} The LESS technique was first introduced to endoscopic parathyroidectomy in 2011, ¹³ and transareola single-site endoscopic thyroidectomy (TASSET) has been successfully established as a surgical approach associated with improved cosmetic results and minimal invasiveness. ¹⁴

The present study aimed to demonstrate the possible advantages or drawbacks associated with TASSET compared with MIVAT, particularly in terms of operative time and cosmetic results.

Patients and methods

Study Population

This study included consecutive patients undergoing thyroid nodule surgery at the Fengxian Central Hospital, Shanghai, China, between January 2011 and March 2012. Patients were randomized (using a computer-generated randomization schedule) to receive TASSET or MIVAT. Inclusion criteria were: a single benign thyroid nodule tumour that was < 30 mm in maximum diameter (volume < 20 ml, assessed by computed tomography scan) and no previous history of thyroiditis, neck surgery or irradiation. There were no exclusion criteria specified for the study.

The study was approved by the Ethics Committee of Fengxian Central Hospital (No. FH2011032203), and all participants gave their written informed consent before any study procedure was initiated.

Surgical Techniques

The TASSET procedure was characterized by a 20-mm incision delineated along the ipsilateral areola margin of the lesion side. A subcutaneous narrow tunnel from the areola to the anterior neck area was bluntly dissected in the anterior surface of the pectoralis major muscle and clavicle, under endoscopic guidance. A space between the platysma and strap muscles was created with ultrasonic shears (Harmonic Scalpel; Johnson & Johnson Medical, Cincinnati, OH, USA). After longitudinally incising the medial border of the sternohyoid and sternothyroid muscles, the ipsilateral strap muscles were suspended anteriorly and laterally with transcutaneous Prolene™ sutures. Through this incision, a 10-mm trocar was first inserted to pump CO2 into the cavity, with pressure maintained at 6 – 8 mm Hg, and a 30° 10-mm rigid laparoscope (Stryker Endoscopy, CA, USA) was used to visualize the operative space throughout the procedure. A 5-mm trocar was medially inserted for the dissection under endoscopic vision. A harmonic scalpel, dissection stick or electronic knife could be used interchangeably during the procedure. The middle thyroid vein and inferior thyroid vessels were identified and divided. After the isthmus was divided, the lower lobe of the thyroid gland was drawn upward and dissected bluntly. The inferior parathyroid gland was identified and carefully preserved with an intact blood supply. The superior thyroid vessels were identified and dissected close to the thyroid gland, to avoid injuring the superior laryngeal nerve. The recurrent laryngeal nerve was traced and dissected with great care during the complete lobectomy procedure. The resected specimen was placed into a removal bag, then extracted through the subcutaneous cavity to the skin incision and sent for frozen histological examination. After adequate irrigation, a single drain was placed in the cavity through the skin incision. The midline raphe of the strap muscles and the skin incision were closed with absorbable sutures.

The MIVAT procedure was performed through a 2-cm central incision made 2 – 2.5 cm above the sternal notch. The midline was incised and the strap muscles were bluntly dissected from the underlying thyroid isthmus. From this point on, a 5-mm 30° endoscope was used to visualize the external branch of the superior and recurrent laryngeal nerve, and the parathyroid glands. The vessels were dissected and ligated with an ultrasonic scalpel (Ethicon Endo-Surgery, Cincinnati, OH, USA) until the lobe was completely freed and extracted through the skin incision. Haemostasis was ensured after adequate irrigation, and a small drain was placed in the thyroid bed. The strap muscles and skin incision were closed with absorbable sutures.

Assessment of Surgical Outcome

During hospitalization, serum calcium levels were measured in all patients using standard laboratory techniques, to assess any potential damage to the parathyroid. Patients in both groups underwent laryngoscopic examinations for evaluation of recurrent laryngeal nerve status before surgery and on the third postoperative day. Postoperative pain was assessed by means of a visual analogue scale (VAS), which ranged from 0 “no pain ” to 10 “worst pain imaginable ”. ¹⁵ Cosmetic results were evaluated by the patient using both a numerical scale ranging between 0 (worst) and 10 (best), and a verbal response scale ranging between 1 (poor), 2 (accepted), 3 (good) and 4 (excellent). ³

The following parameters were analysed between groups: age; sex; diameter of nodule; preoperative diagnosis; operative time; blood loss; length of hospital stay; complications; cosmetic results.

Statistical Analyses

Statistical analyses were performed using SPSS^® statistical software, version 17.0 (SPSS Inc., Chicago, IL, USA) for Windows^®. Data were expressed as mean ± SD. Comparisons between groups were performed using Student's t-test, Fisher's exact test and the Mann–Whitney U-test. A P-value < 0.05 was considered statistically significant.

Results

In total, 48 patients were randomized to receive TASSET (n = 24) or MIVAT (n = 24). Patient characteristics are presented in Table 1. The two groups were well matched for age, sex and mean diameter of the thyroid nodule. No difference was found between the two groups concerning the preoperative and final pathological diagnosis of thyroid nodules.

Table 1:

Demographic and clinical characteristics of patients who underwent transareola single-site endoscopic thyroidectomy (TASSET) or minimally invasive video-assisted thyroidectomy (MIVAT)

Characteristic	TASSET n = 24	MIVAT n = 24
Female/male	23/1	23/1
Age, years	33.53 ± 10.12	32.05 ± 9.05
Diameter of nodule, mm	2.13 ± 0.51	2.08 ± 0.66

Data presented are n patients or mean ± SD.

There were no statistically significant between-group differences (P ≥ 0.05); comparisons between groups were performed using Fisher's exact test and the Mann–Whitney U-test.

All thyroidectomies were performed successfully. There were no significant differences in surgical procedures, estimated blood loss or length of postoperative stay (Table 2). The mean operative time was significantly longer with TASSET compared with MIVAT (P < 0.01; Table 2). In the group receiving the TASSET procedure, the mean ± SD operation time was significantly reduced from 168.67 ± 14.33 min to 143.86 ± 18.30 min for cases 1 to 12 and cases 13 to 24, respectively (P < 0.05).

Table 2:

Surgical characteristics and outcomes in patients who underwent transareola single-site endoscopic thyroidectomy (TASSET) or minimally invasive video-assisted thyroidectomy (MIVAT)

Characteristic	TASSET n = 24	MIVAT n = 24	Statistical significancea
Surgical procedure			NS
Total lobectomy	12 (50.0)	11 (45.8)
Subtotal lobectomy	11 (45.8)	12 (50.0)
Subtotal thyroidectomy	1 (4.2)	1 (4.2)
Operation time, min	156.84 ± 41.42	66.38 ± 17.58	P < 0.01
Operative blood loss, ml	27.11 ± 6.08	25.24 ± 6.80	NS
Postoperative stay, days	2.5 (2 – 4)	2.3 (2 – 4)	NS

Data presented as n (%) of patients, mean ± SD or median (range).

NS, not statistically significant (P ≥ 0.05); comparisons between groups were performed using Student's t-test and the Mann–Whitney U-test.

Patients in the TASSET group had significantly improved cosmetic results according to the numerical scale compared with those in the MIVAT group (mean ± SD 9.63 ± 0.60 versus 7.90 ± 1.38, respectively; P < 0.05), and significantly higher scores for the verbal response scale (mean ± SD 3.8 ± 0.5 versus 3.1 ± 0.7, respectively; P < 0.05).

No significant between-group difference was found regarding surgical complications. Two patients developed subcutaneous seromas and one patient developed tracheal injury after TASSET. One patient developed transient paralysis of the recurrent laryngeal nerve and one patient developed transient hypocalcaemia following MIVAT. There was no significant difference between groups in bleeding rate, wound infection, permanent recurrent laryngeal nerve injury or persistent hypocalcaemia. The mean VAS score for postoperative pain was 2 (0 – 4) for both groups. No patient required analgesia.

Discussion

Conventional thyroid surgery has reached a very high therapeutic standard and offers a very high level of safety, ¹⁶ but it leaves a visible scar on the anterior surface of the neck that results in a permanent cosmetic defect, frequent cervical hyperaesthesia or paraesthesia. ¹⁷ As thyroid disease is prevalent in young women, cosmetic outcome is an important consideration in thyroid surgery. ¹⁸ Since endoscopic neck surgery was first described in 1996, ⁴ endoscopic procedures based on various approaches have been widely applied. Studies have shown that video-assisted^19,20 and endoscopic ²¹ procedures for thyroid surgery have some advantages over conventional surgery in terms of cosmetic results and postoperative recovery. MIVAT is characterized by a minimal cervical incision (∼2 cm), and safe dissection from the cervical incision. ³ MIVAT has been found to be reproducible and has become very popular, with an excellent success rate and a good cosmetic outcome. ²² MIVAT is suggested to be a technique with a good safety profile that requires 25 – 30 cases for a correct learning curve, for an experienced surgeon. ²³ Endoscopic thyroidectomy has not always been minimally invasive, however. Conventional endoscopic thyroidectomy requires the creation of three subcutaneous tunnels from skin incisions; therefore, relatively wider subcutaneous tissue is dissected, causing more incisions and more postoperative pain when compared with conventional surgery. To overcome the invasiveness and pain, single-site endoscopic thyroidectomy has been increasingly used because of its narrow dissection area approaching the operation site and better cosmetic outcome, compared with conventional endoscopic procedures.^3,24 Youben et al. ²⁵ described several advantages of the TASSET approach in thyroidectomy. First, there is an excellent cosmetic outcome because a single scar on the circumareolar margin blends with the colour of the areola. Secondly, the recurrent laryngeal nerve and parathyroid gland can be easily identified and carefully preserved. Finally, the TASSET approach is superior to the axillary approach for bilateral nodules. The single-site endoscopic thyroidectomy requires patience and a particularly sophisticated skillset. There are no commercial single-port devices in China, and single-port devices are not covered by medical insurance. Consequently, commonly available devices in laparoendoscopic surgery are used in China, which makes the procedure economical and acceptable for patients.

The two groups in the present study were well matched in terms of age, sex, and surgical indications. Patients were selected on the basis of strong inclusion criteria: only small (< 30 mm) and benign thyroid nodules were included in this study. Intraoperative outcomes were equivalent between the two procedures. From a technical standpoint, intraoperative issues (such as adequate exposure of the thyroid vessel, thyroid and parathyroid glands) could be achieved using TASSET. The dissection level was located in loose connective tissue in the chest wall, without injury to the mammary gland or duct, and located under the platysma in the neck. Transcutaneous suture was used to elevate strap muscles adequately and obtain good thyroid exposure. Thus, there was no need for grasping forceps or a third trocar. A low-profile 5-mm tube was also used to minimize the instrumental crushing, instead of a long 5-mm trocar. There was no significant between-group difference in postoperative outcomes such as pain, length of hospital stay, thyroglobulin level or permanent vocal cord palsy. In addition, no significant difference was found in terms of postoperative complications. During the TASSET procedure, surgical instruments were placed close to each other, which limited their angles of movement and caused clashing or mutual interference of instruments, which made the procedure relatively more difficult to perform. Thus, the mean operative time was significantly longer for TASSET than for MIVAT. These data are comparable with data from other published studies.^13,25,26 Compared with the first 12 cases, the operative time decreased by ∼26 min in the second 12 cases, suggesting that the operative time for TASSET gradually decreased with increased experience. A learning curve must always be accounted for when a new surgical technique is initiated. Continual troubleshooting between the surgeons should ensure smooth completion of surgery, even though all single-site procedures were performed by surgeons with considerable endoscopic experience.

The cosmetic outcome, evaluated by a numerical scale and verbal response scale, was significantly in favour of TASSET. The mean score of the verbal response scale in both groups was > 3, suggesting that the majority of patients were satisfied with cosmetic results after both procedures. It seems reasonable that an extracervical scar hidden by clothes is better than a cervical scar.

In conclusion, TASSET is a feasible procedure with a relatively good safety profile. A surgeon with experience in conventional endoscopic thyroidectomy will perform it without any difficulty. Although MIVAT involves a shorter operation time, TASSET offers advantages for selected patients in terms of improved cosmetic results, with comparable postoperative outcomes and complication rates. Although further prospective studies involving a larger series of patients are necessary, the present results suggest that TASSET is a valid option for selected patients for the surgical treatment of thyroid disease.